Why am I so hungry all of the time?

I had really bad diarrhoea 2 weeks ago for 3/4 days and since then all I have done is eat!! Yesterday, I felt like I was eating non stop. I seem to just be eating junk food, healthy food doesn't interest me at the moment. I have tried to just stick to 3 normal sized meals a day, but I keep going light headed and feel that I might pass out and my stomach rumbles really loudly! Should I go to the doctors and see if they can do anything? Would they be able to do anything?